System and method for repairing a gas turbine vane

Abstract

A stationary turbine vane includes an outer shroud, an inner shroud, a vane extending between the outer shroud and the inner shroud, and an air tube positioned within the vane and operable to conduct a flow of cooling air through a tube passage formed as part of one of the inner shroud and the outer shroud. An insert having a first end, a second end, and a collar is fixedly attached to one of the inner shroud and the outer shroud to position the first end outside of the vane and to position one of the second end and a portion of the air tube inside the other of the second end and the portion of the air tube. The air tube is arranged to one of receive or discharge the flow of cooling air to cool the vane.

Description

SYSTEM AND METHOD FOR REPAIRING A GAS TURBINE VANEBACKGROUND

[0001] Gas turbines engines operate by burning a fuel to produce a high-temperature exhaust gas that turns a turbine and drives a device such as a generator. The high-temperature gas sometimes requires the use of turbine components that are cooled. For example, turbine blades and vanes may include cooling features that allow the blades to operate for longer periods of time in the high-temperature environment. However, some components of these cooling arrangements may periodically require repair or replacement.SUMMARY

[0002] In one aspect, a stationary turbine vane includes an outer shroud, an inner shroud, a vane extending between the outer shroud and the inner shroud, and an air tube positioned within the vane and operable to conduct a flow of cooling air through a tube passage formed as part of one of the inner shroud and the outer shroud. An insert having a first end, a second end, and a collar is fixedly attached to one of the inner shroud and the outer shroud to position the first end outside of the vane and to position one of the second end and a portion of the air tube inside the other of the second end and the portion of the air tube. The air tube is arranged to one of receive or discharge the flow of cooling air to cool the vane.

[0003] The stationary turbine vane may also position a portion of the air tube within the second end of the insert.

[0004] The stationary turbine vane may also include an insert that includes an inner wall that defines a flow path that extends between the first end and the second end, the inner wall having an oval cross-section taken normal to a direction of flow through the flow path.

[0005] The stationary turbine vane may also include an insert that includes an outer wall, and where the collar includes a contact surface that extends completely around the outer wall.

[0006] The stationary turbine vane may also include a collar that is welded to the inner shroud.

[0007] The stationary turbine vane may also include an insert that includes an outer wall, and where an inner chamfer is formed at the second end of the inner wall and an outer chamfer is formed at the second end of the outer wall.

[0008] The stationary turbine vane may also be arranged such that a portion of the contact surface cooperates with the outer wall to define an oblique angle therebetween.

[0009] The stationary turbine vane may also include an insert that includes a collar wall that extends at an oblique angle to and completely around the outer wall.

[0010] The stationary turbine vane may also include an inner shroud that includes a cover plate and where the collar contacts the cover plate. Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.

[0011] In one aspect, a method of repairing a stationary turbine vane without removing the stationary turbine vane from a stationary vane group includes removing a damaged portion of an air tube from a stationary turbine vane that includes an outer shroud, an inner shroud, and a vane extending between the outer shroud and the inner shroud. The method also includes positioning a first end of an insert outside of the vane, and inserting a second end of the insert into the stationary turbine vane such that one of the second end and a portion of the air tube is disposed within the other of the second end and the portion of the air tube. The method further includes abutting a collar of the insert against one of the inner shroud and the outer shroud, and welding the collar to the one of the inner shroud and the outer shroud to fixedly attach the insert to the stationary turbine vane.

[0012] The method may also include an inserting step that includes inserting the portion of the air tube into the second end of the insert.

[0013] The method may also include using a collar that includes a contact surface that extends completely around the collar and abuts the inner shroud.

[0014] The method may also include performing the repair in-situ.

[0015] The method may also include using an inner shroud that includes a cover plate and where the collar abuts the cover plate. Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0016] To easily identify the discussion of any particular element or act, the most significant digit or digits in a reference number refer to the figure number in which that element is first introduced.

[0017] FIG. 1 is a longitudinal cross-sectional view of a gas turbine engine taken along a plane that contains a longitudinal axis or central axis.

[0018] FIG. 2 is a perspective view of a stationary vane group suitable for use in the gas turbine engine of FIG. 1.

[0019] FIG. 3 is a radial or bottom view of a portion of the stationary vane group of FIG. 2.

[0020] FIG. 4 is a perspective view of an insert suitable for use in repairing the stationary vane group of FIG. 2.

[0021] FIG. 5 is a perspective view of the insert of FIG. 4 inserted into the stationary vane group of FIG. 2.

[0022] FIG. 6 is a cross-sectional view of a portion of the stationary vane group of FIG. 2 with the insert of FIG. 4 installed.DETAILED DESCRIPTION

[0023] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in this description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0024] Various technologies that pertain to systems and methods will now be described with reference to the drawings, where like reference numerals represent like elements throughout. The drawings discussed below, and the various embodiments used to describe the principles of the present disclosure in this patent document are by way of illustration only and should not be construed in any way to limit the scope of the disclosure. Those skilled in the art will understand that the principles of the present disclosure may be implemented in any suitably arranged apparatus. It is to be understood that functionality that is described as being carried out by certain system elements may be performed by multiple elements. Similarly, for instance, an element may be configured to perform functionality that is described as being carried out by multiple elements. The numerous innovative teachings of the present application will be described with reference to exemplary non-limiting embodiments.

[0025] It should be understood that the words or phrases used herein should be construed broadly, unless expressly limited in some examples. For example, the terms “including,” “having,” and “comprising,” as well as derivatives thereof, mean inclusion without limitation. The singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. Further, the term “and / or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. The term “or” is inclusive, meaning and / or, unless the context clearly indicates otherwise. The phrases “associated with” and “associated therewith,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like. Furthermore, while multiple embodiments or constructions may be described herein, anyfeatures, methods, steps, components, etc. described with regard to one embodiment are equally applicable to other embodiments absent a specific statement to the contrary.

[0026] Also, terms such as “first”, “second”, “third” and so forth may be used herein to refer to various elements, information, functions, or acts, but should not be considered as limiting in any way. Rather these numeral adjectives are used to distinguish different elements, information, functions or acts from each other. For example, a first element, information, function, or act could be termed a second element, information, function, or act, and, similarly, a second element, information, function, or act could be termed a first element, information, function, or act, without departing from the scope of the present disclosure.

[0027] In addition, the term “adjacent to” may mean that an element is relatively near to but not in contact with a further element or that the element is in contact with the further portion unless the context clearly indicates otherwise. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise. Terms “about” or “substantially” or like terms are intended to cover variations in a value that are within normal industry manufacturing tolerances for that dimension. If no industry standard is available, a variation of twenty percent would fall within the meaning of these terms unless otherwise stated.

[0028] FIG. 1 illustrates an example of a gas turbine engine 100 including a compressor section 104, a combustion section 102, and a turbine section 106 arranged along a central axis 122. The compressor section 104 includes a plurality of compressor stages 108 with each compressor stage 108 including a set of rotating blades 126 and a set of stationary vanes 124 or adjustable guide vanes. A rotor 128 supports the rotating blades 126 for rotation about the central axis 122 during operation. In some constructions, a single one-piece rotor 128 extends the length of the gas turbine engine 100 and is supported for rotation by a bearing at either end. In other constructions, the rotor 128 is assembled from several separate spools that are attached to one another or may include multiple disk sections that are attached via a bolt or plurality of bolts.

[0029] The compressor section 104 is in fluid communication with an inlet section 116 to allow the gas turbine engine 100 to draw atmospheric air into the compressor section 104. During operation of the gas turbine engine 100, the compressor section 104 draws inatmospheric air and compresses that air for delivery to the combustion section 102. The illustrated compressor section 104 is an example of one compressor section 104 with other arrangements and designs being possible.

[0030] In the illustrated construction, the combustion section 102 includes a plurality of separate combustors 112 that each operate to mix a flow of fuel with the compressed air from the compressor section 104 and to combust that air-fuel mixture to produce a flow of high temperature, high pressure combustion gases or exhaust gas 118. Of course, many other arrangements of the combustion section 102 are possible.

[0031] The turbine section 106 includes a plurality of turbine stages 110 with each turbine stage 110 including a number of rotating blades and a number of stationary blades or vanes. The turbine stages 110 are arranged to receive the exhaust gas 118 from the combustion section 102 at a turbine inlet 114 and expand that gas to convert thermal and pressure energy into rotating or mechanical work. The turbine section 106 is connected to the compressor section 104 to drive the compressor section 104. For gas turbine engines 100 used for power generation or as prime movers, the turbine section 106 is also connected to a generator, pump, or other device to be driven. As with the compressor section 104, other designs and arrangements of the turbine section 106 are possible.

[0032] A control system 120 is coupled to the gas turbine engine 100 and operates to monitor various operating parameters and to control various operations of the gas turbine engine 100. In preferred constructions the control system 120 is typically micro-processor based and includes memory devices and data storage devices for collecting, analyzing, and storing data. In addition, the control system 120 provides output data to various devices including monitors, printers, indicators, and the like that allow users to interface with the control system 120 to provide inputs or adjustments. In the example of a power generation system, a user may input a power output set point and the control system 120 may adjust the various control inputs to achieve that power output in an efficient manner.

[0033] The control system 120 can control various operating parameters including, but not limited to variable inlet guide vane positions, fuel flow rates and pressures, engine speed, valve positions, generator load, and generator excitation. Of course, other applications may have fewer or more controllable devices. The control system 120 also monitors various parametersto assure that the gas turbine engine 100 is operating properly. Some parameters that are monitored may include inlet air temperature, compressor outlet temperature and pressure, combustor outlet temperature, fuel flow rate, generator power output, bearing temperature, and the like. Many of these measurements are displayed for the user and are logged for later review should such a review be necessary.

[0034] FIG. 2 illustrates a stationary vane group 200 suitable for use in the engine of FIG. 1. The stationary vane group 200 includes four stationary turbine vanes 202 that are connected to one another by an outer shroud 204 and an inner shroud 206. While the illustrated stationary vane group 200 includes four stationary turbine vanes 202, other arrangements could include a single stationary turbine vane 202, fewer than four stationary turbine vanes 202, or more than four stationary turbine vanes 202 as desired for the particular design.

[0035] Each stationary turbine vane 202 includes a vane 208 that extends between the outer shroud 204 and the inner shroud 206 and that cooperates with an adjacent vane 208 to define a gas passage 212 therebetween. In the illustrated construction, each vane 208 is welded to the outer shroud 204 and the inner shroud 206 to define a single fixed component. However, other constructions may employ different attachment methods in place of or in conjunction with welding.

[0036] The stationary vane group 200 provides several gas passages 212 that define a flow path for the hot exhaust gas 118 generated in the combustor 112. The stationary vane group 200 operates to redirect the exhaust gas 118 for entry into a row of rotating blades 126. In the illustrated construction, each vane 208 is hollow to allow for a flow of cooling air through the vane 208. An air tube 210 is positioned within each vane 208 to facilitate the passage of the flow of cooling air through the vane 208.

[0037] FIG. 3 illustrates a portion of the stationary vane group 200 looking outward radially (bottom view). As illustrated, each air tube 210 is an oval shaped tube that extends radially outward (or above) the inner shroud 206. An opening or tube passage 304 is formed as part of the inner shroud 206 to allow for the passage of a portion of the air tube 210 through the inner shroud 206.

[0038] In some constructions, cover plates 302 are formed on an outer surface of the inner shroud 206 with each one surrounding one of the air tubes 210. The cover plates 302 may beformed as part of the inner shroud 206 or attached to the inner shroud 206. In addition, some constructions may include cover plates 302 that surround more than one air tube 210 or may omit the cover plates 302 completely.

[0039] During operation, the exposed portion of the air tubes 210 may wear or erode ultimately degrading the operation of the vane 208 or vanes 208. To repair damaged air tubes 210, it was required to remove the stationary vane group 200 that included the damaged air tube 210 and ship that damaged component to a specialized repair facility. The damaged air tube 210 was then repaired or replaced in a factory setting.

[0040] It should also be noted that while the figures and description describe a repair to an air tube 210 that extends through the inner shroud 206 other applications may provide for the repair of an air tube 210 that extends through an outer shroud 204. The actual shroud through which the air tube 210 protrudes is not critical to the repair.

[0041] FIG. 4 through FIG. 6 illustrate an insert 400 and a method of using the insert 400 to facilitate the repair of a damaged air tube 210 in-situ. As used herein, “in-situ” means that the damaged air tube 210 is repaired at or near the operating location of the gas turbine engine 100 and more preferably is repaired without removing the stationary vane group 200 from its blade carrier or casing if possible. Any repair that is carried out without the need of a specialized facility or specialized training may be considered “in-situ”. Performing the repair in-situ greatly reduces the time, effort, and cost required to perform such a repair.

[0042] With reference to FIG. 4, the insert 400 includes a first end 402, a second end 404, an inner wall 406, and an outer wall 408. The inner wall 406 and outer wall 408 are arranged to define an oval cross-section when taken normal to the flow of cooling air 214. Of course, other shapes would be selected as needed to closely match the shape of the air tube 210. The inner wall 406 defines a flow path 410 that extends the length of the insert 400 between the first end 402 and the second end 404. It should be noted that the flow of cooling air 214 is illustrated and described herein as traveling from the outer shroud 204 toward the inner shroud 206. In addition, the air tube 210 is described as having a first end 402 and a second end 404 that correspond with this flow direction. However, in other arrangements or other operating conditions, this flow direction could reverse. As such, these terms and directions should not be read as limiting the arrangement in any way.

[0043] A collar 412 extends around the perimeter of the outer wall 408 and separates the first end 402 from the second end 404. The collar 412 includes a contact surface 414 and a collar wall 416 that each extend around the perimeter of the outer wall 408 and give the collar 412 a triangular cross section. The contact surface 414 is preferably planar and is arranged to closely contact the cover plate 302 when the insert 400 is placed in its installed or operating position. In arrangements in which the inner shroud 206 is frustoconical (as illustrated in FIG. 6), the plane of the contact surface 414 is angled obliquely with respect to the direction of flow of the flow of cooling air 214 such that the flow of cooling air 214 enters (or exits in other arrangements) the vane 208 in a substantially radial direction (with respect to the central axis 122 of the gas turbine engine 100) after the insert 400 is installed.

[0044] The collar wall 416 is conical and extends from the outer wall 408 of the insert 400 to an outermost perimeter of the contact surface 414. The taper or angle of the collar wall 416 cooperates with the outer wall 408 to define an oblique angle therebetween. However, this arrangement is not critical, but rather is selected for ease of manufacture and the reduction of any sharp corners at the intersections with the collar wall 416.

[0045] As will be discussed with regard to FIG. 6, the inner wall 406 includes an inner chamfer 418 formed at the second end 404 of the insert 400 and an outer chamfer 420 formed at the second end 404 of the outer wall 408. The inner chamfer 418 and the outer chamfer 420 are provided to facilitate assembly of the insert 400 into the vane 208.

[0046] FIG. 5 illustrates a portion of the insert 400 including the collar 412 and the first end 402 in an installed or operating position. As illustrated, the contact surface 414 engages or rests on the cover plate 302 or directly onto the inner shroud 206. A weld 502 is placed around the perimeter of the collar 412 to fixedly attach the insert 400 to the inner shroud 206 or the cover plate 302. The weld 502 could be applied using any known welding process suited to the task and the materials used to manufacture the insert 400 and the cover plate 302 or inner shroud 206. In other constructions, a braze or solder joint is employed to attach the insert 400 to the cover plate 302 or inner shroud 206. The joining method used is selected based on the expected operating conditions, the materials used, and the available processes at the location of the repair. So long as the joint provides the necessary strength and sealably attaches the insert 400 to the cover plate 302 or the inner shroud 206, the actual method used is not critical.

[0047] FIG. 6 is a sectional view of a portion of the stationary vane group 200 with the insert 400 installed in one of the vanes 208. FIG. 6 clearly illustrates the frustoconical shape of the inner shroud 206 and the matching oblique angle between the contact surface 414 and the direction of flow of the flow of cooling air 214. It should be clear that the contact surface 414 cooperates with at least a portion of the outer wall 408 to define an oblique angle therebetween as well.

[0048] The inner chamfer 418 and the outer chamfer 420 of the insert 400 aid in the installation of the insert 400 into an air tube opening 602 in which the air tube 210 is positioned. The air tube opening 602 and the air tube 210 provide a clearance space for the insert 400 which may be restricted.

[0049] After operation for a period of time, the exposed portion of some of the air tubes 210 in a row of stationary vanes 124 may become damaged. To repair that damage, the stationary vane group 200 that includes the damaged air tube 210 is removed from the gas turbine engine 100 to allow free access to the repair location.

[0050] The damaged portion of the air tube 210 is removed using a grinding or machining operation. Typically, a flat end grinding burr is well-suited to removing the damaged portion of the air tube 210. However, any suitable technique may be employed as desired. Preferably, the exposed portion of the air tube 210 is completely removed such that the end of the air tube 210 is flush with the outermost surface of the inner shroud 206 as illustrated in FIG. 6.However, it is not critical that the air tube 210 be flush with the inner shroud 206 as it could extend beyond the inner shroud 206 or could be lower than or inside the inner shroud 206 as may be required based on the damage. Sufficient portions of the air tube 210 should be removed to assure that the remainder of the air tube 210 is in a suitable condition to continue operation of the gas turbine engine 100.

[0051] Next, if not already formed or if damaged, the cover plate 302 is positioned in the desired operating position or the existing cover plate 302 is repaired to provide a suitable surface for receiving the contact surface 414 of the insert 400.

[0052] The second end 404 of the insert 400 is inserted into the air tube opening 602 that holds the air tube 210 such that the outer wall 408 is adjacent the walls of the air tube opening 602 and the inner wall 406 surrounds and receives the end portion of the air tube 210. Asmentioned, the inner chamfer 418 and the outer chamfer 420 of the insert 400 aid in the installation of the insert 400 around the air tube 210 and within the air tube opening 602.While an airtight seal is not required, a close fit is desirable to reduce leakage within the vane 208.

[0053] Once the insert 400 is positioned as illustrated in FIG. 6, the weld 502, or other attachment joint, can be formed to sealably and fixedly attach the insert 400 to the inner shroud 206 or the cover plate 302, thereby completing the repair.

[0054] In operation, the flow of cooling air 214 passes through the vane 208 and the air tube 210 as it did prior to the repair. However, rather than entering or exiting via the air tube 210, the flow of cooling air 214 enters or exits the first end 402 of the insert 400, and flows to or from the first end 402 via the second end 404 of the insert 400, and the flow path 410. Thus, the insert 400 becomes part of the total flow path for the flow of cooling air 214.

[0055] Using this repair eliminates the need to ship the stationary vane group 200 to a facility suited to repairing the air tube 210, thereby saving time and cost while still providing a high- quality repair.

[0056] Although an exemplary embodiment of the present disclosure has been described in detail, those skilled in the art will understand that various changes, substitutions, variations, and improvements disclosed herein may be made without departing from the spirit and scope of the disclosure in its broadest form.

[0057] None of the description in the present application should be read as implying that any particular element, step, act, or function is an essential element, which must be included in the claim scope: the scope of patented subject matter is defined only by the allowed claims. Moreover, none of these claims are intended to invoke a means plus function claim construction unless the exact words "means for" are followed by a participle.

Claims

CLAIMSWhat is claimed is:

1. A stationary turbine vane comprising: an outer shroud; an inner shroud; a vane extending between the outer shroud and the inner shroud; an air tube positioned within the vane and operable to conduct a flow of cooling air through a tube passage formed as part of one of the inner shroud and the outer shroud; and an insert having a first end, a second end, and a collar, the collar fixedly attached to one of the inner shroud and the outer shroud to position the first end outside of the vane and to position one of the second end and a portion of the air tube inside the other of the second end and the portion of the air tube, the air tube arranged to one of receive or discharge the flow of cooling air to cool the vane.

2. The stationary turbine vane of claim 1, wherein a portion of the air tube is positioned within the second end of the insert.

3. The stationary turbine vane of claim 1, wherein the insert includes an inner wall that defines a flow path that extends between the first end and the second end, the inner wall having an oval cross-section taken normal to a direction of flow through the flow path.

4. The stationary turbine vane of claim 3, wherein the insert includes an outer wall, and wherein an inner chamfer is formed at the second end of the inner wall and an outer chamfer is formed at the second end of the outer wall.

5. The stationary turbine vane of claim 1, wherein the insert includes an outer wall, and wherein the collar includes a contact surface that extends completely around the outer wall.

6. The stationary turbine vane of claim 5, wherein a portion of the contact surface cooperates with the outer wall to define an oblique angle therebetween.

7. The stationary turbine vane of claim 5, wherein the insert includes a collar wall that extends at an oblique angle to and completely around the outer wall.

8. The stationary turbine vane of claim 1, wherein the collar is welded to the inner shroud.

9. The stationary turbine vane of claim 8, wherein the inner shroud includes a cover plate and wherein the collar contacts the cover plate.

10. A method of repairing a stationary turbine vane without removing the stationary turbine vane from a stationary vane group, the method comprising: removing a damaged portion of an air tube from a stationary turbine vane that includes an outer shroud, an inner shroud, and a vane extending between the outer shroud and the inner shroud; positioning a first end of an insert outside of the vane; inserting a second end of the insert into the stationary turbine vane such that one of the second end and a portion of the air tube is disposed within the other of the second end and the portion of the air tube; abutting a collar of the insert against one of the inner shroud and the outer shroud; and welding the collar to the one of the inner shroud and the outer shroud to fixedly attach the insert to the stationary turbine vane.

11. The method of claim 10, wherein the inserting step includes inserting the portion of the air tube into the second end of the insert.

12. The method of claim 10, wherein the collar includes a contact surface that extends completely around the collar and abuts the inner shroud.

13. The method of claim 12, wherein the inner shroud includes a cover plate and wherein the collar abuts the cover plate.

14. The method of claim 10, wherein the repair is performed in-situ.

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